ABSTRACT
A lake or a reservoir is intimately related with a watershed—a biogeophysical boundary—that is a drainage system connecting these natural or artificial bodies of water. Pristine watersheds not subjected to extensive modification by human activities contribute with low input of nutrients, suspended material, or toxic substances to the lakes and reservoirs. Any lake or reservoir in a watershed depends upon a matrix of geological, hydrogeochemical, climatologically natural characteristics and of the human activities imposed upon these natural features. Lakes and reservoirs are subjected to several types of sudden changes of natural or man-induced origin, which affects many physical, chemical, and biological variables. Even considering the limnological similarities between lakes and reservoirs, there are some differences that have to be described, because these are fundamental for management purposes. The knowledge on the hydrodynamics of lakes and reservoirs coupled with studies on the water quality is limited to a few groups of these ecosystems mainly in temperate regions.
